This invention relates to rigid core formers for use in the construction of concrete or other structures.
It is among the objects of the present invention to provide a rigid core former which is simple to erect and use, and one which can be used repeatedly without the need to completely dismantle it each time it is used.
According to the present invention, there is provided a rigid core former comprising a pair of interengaging former elements each element having at least one forming surface, a resilient sleeve surrounding the former elements and serving normally to bias them into a first position, and means for moving the former elements relative to one another, against the action of the resilient sleeve, into a second position.
Preferably, the resilient sleeve is of rubber and the means for moving the former elements relative to one another are pneumatic means in the form of an inflatable rubber or other tube.